Alternator wiring confused

[jamesroney]

70?? . . . and I thought I was old school with my 84 copy. . .
plus I am sure that those numbers have all been revised due to "global warming"

I pulled this data from a bootleg copy of the NFPA 70, version 2023. But it is largely unchanged from the widely adopted NFPA 70, version 2017.

And yes, "NFPA 70" is a registered trademark of the National Fire Prevention Association, And yes, it's the one adopted by all 50 states in some version or the other. And yes, it's a silly name for the National Electric Code.

Is your Bronco running?

 

[jamesroney]

Is there a difference between solid conductor versus stranded?

Since AWG is determined by cross sectional area of the conductors, and not by Outside Diameter of the wire....the answer is "no."

In the event of some High Frequency (like RF) transmission, the answer is "maybe."

I gotta get back to working on my Bronco...

 

[Nowik35]

I wish I knew this conversation before I bought my alternator so I'm just going to make the one I already bought work with the external regulator.
Next question. Looks like on original wiring diagram the i terminal from the starter solenoid gets spliced into the #16 coil resistor wire . Am I correct? Since I don't have this wire anymore I'm going to use the ballast resistor. So another 14g pink wire from ignition to ballast resistor then to ignition coil. So the question is where should my final destination be on the I wire coming from starter solenoid? I know the s wire from the starter solenoid goes to the s on the ignition.

 

[Oldtimer]

The "I" terminal on starter relay is to supply full 12 volts to coil when starting engine.
Typically a Brown wire.
You can run it direct to coil + terminal, or tie it to the coil side of the ballast resistor.

 

[Oldtimer]

Is your Bronco running?

Is this week.
Actually drove it to SuperCel Nevada last month.

 

[Nowik35]

Thank you that makes sense now. One more question. What is the purpose of the direct wire from s terminal of the voltage regulator directly to the ignition?

 

[DirtDonk]

I wish I knew this conversation before I bought my alternator so I'm just going to make the one I already bought work with the external regulator.

Easy enough to do. You just have to make some new branches of the harness with your own wiring. Pretty simple.
The harness companies want to simplify it for a good reason. But the little extra work you’ll have to go through won’t be the end of the world.

Next question. Looks like on original wiring diagram the i terminal from the starter solenoid gets spliced into the #16 coil resistor wire . Am I correct?

Yes. As said it supplies extra voltage, while the starter is cranking. It’s not actually spliced into the resistor wire, per se, as much it is spliced in AFTER the resistor wire.

Since I don't have this wire anymore I'm going to use the ballast resistor.

Do you need it? What ignition system are you running?
If you haven’t decided yet, or haven’t purchased any new components that you are going to run, simply buy an ignition coil and ignition system/distributor/ICM that are designed to run on the full 12v instead.
No heat producing ballast resistor needed, fewer extra connections and spices, and problem solved.
In theory…

 

[DirtDonk]

What is the purpose of the direct wire from s terminal of the voltage regulator directly to the ignition?

It simply tells the regulator, and through that the alternator, that it’s time to get to work.
The engine can spin the alternator all it wants, but without a little power supplied to the regulator to energize it, or excite it, the alternator won’t know to charge.

 

[DirtDonk]

Those two wires, the red with green stripe and the green with red stripe, or whatever colors they are in your new harness, are on the same terminal on the back of the ignition switch.
This terminal is the only one that, by itself, is hot in both ON and the START positions.
And does not have any power when the key is in the ACC position.

This allows you to listen to the radio in the accessory position while not overheating the ignition or draining the battery through the alternator.

 

[Oldtimer]

See , @Viperwolf1 picture posted by @jamesroney in post #8.

Ignition switch in Run supplies 12v to "S" term (green) of regulator.
This closes internal relay and connects 12v from "A" term (yellow) to "F" term (orange) that is used to energize the field of the alternator.

Edit:
Or what Paul said ^^

 

[jamesroney]

Those two wires, the red with green stripe and the green with red stripe, or whatever colors they are in your new harness, are on the same terminal on the back of the ignition switch.
This terminal is the only one that, by itself, is hot in both ON and the START positions.
And does not have any power when the key is in the ACC position.

This allows you to listen to the radio in the accessory position while not overheating the ignition or draining the battery through the alternator.

Careful here:

The ignition switch is not designed (or required) to have the "I" terminal hot in the START position.

Many people think it is. BUT, the I terminal on the Ignition switch will be back-fed from the "I" terminal on the starter relay thru the resistor wire when the key is in the START position.

(...Of course, many ignition switches DO have the I terminal hot in the start position.)

Some of the early 60's ignition switches will energize the Ignition when the key is in the Start position. Some will only do it at the beginning of the start, and some allow you to twist it past the beginning, and it will drop out at MAX start position.

The 1967-69 Mustang switch with the bigger key is notorious for dropping out ignition when cranking. So the engine will only fire after you stop cranking.

If you've ever installed an EFI harness with the stock ignition switch, you know what I'm saying. Ryan McCormick fixed all of that with his RJM / TDZ / Ron Francis harness design.

I know that you know this, but if someone stumbles on this thread, it's worth noting.

 

[DirtDonk]

Been dying to post up since I saw your post earlier today.
Unusually, I'm going to disagree with, or at least question, most of what you say here.

The ignition switch is not designed (or required) to have the "I" terminal hot in the START position.

Why not? Does it rely only on the Brown "I" wire from the starter relay to keep power to the ignition during START?
I was sure I'd tested several Bronco ignition switches and found that they have power to that terminal in START as well as ON. But maybe I'm thinking of other brand switches.

Many people think it is. BUT, the I terminal on the Ignition switch will be back-fed from the "I" terminal on the starter relay thru the resistor wire when the key is in the START position.

Yes, but are they relying entirely on that function? No need for the switch to supply it, since the starter relay is doing the job? I thought it was only a handy backup to that function and that the switch was (when it was working properly) supplying 12v in START as well.

(...Of course, many ignition switches DO have the I terminal hot in the start position.)

Hence my questions, since I have worked on lots of vehicles (admittedly very casually) over the years.

The 1967-69 Mustang switch with the bigger key is notorious for dropping out ignition when cranking. So the engine will only fire after you stop cranking.

Is that if the starter relay fails? Because if it's all working as planned, the "I" terminal of the relay feeds the coil power during START. So you wold not even notice the power from the switch drop off if the starter relay remains active.

If you've ever installed an EFI harness with the stock ignition switch, you know what I'm saying. Ryan McCormick fixed all of that with his RJM / TDZ / Ron Francis harness design.

In what way was it fixed? The harness connects to the Bronco's original 3-wire connector (or the Centech supplied Weatherpack) for it's ignition power. Is it taking power from a source other than the starter relay's "I" wire while in START? What happens if a later model relay without the same "I" circuit available? You're saying it does not come from the ignition switch?
Lots of us have run EFI (including you many times of course) with modern starter relays, from the stock ignition switch and do not have a dropout issue. Where do the Ryan (et al) and Ford Racing and factory Explorer wiring get it's ECU power from when the ignition switch is in the START position? Not to mention all the aftermarket EFI setups that utilize stock Bronco ignition switches with their EFI harnesses?
We often hear of someone dropping power to their hand-held or other on-board EFI device when using stock Bronco wiring. But connecting to the Red w/green or Green w/red wires eliminates this issue. At least that I remember.
Something must be keeping power in the system. Even without the "I" wire from the starter relay.

I know that you know this, but if someone stumbles on this thread, it's worth noting.

Apparently I didn't at least. And I have posted up many times over the years that the Bronco switch supplies power to both the Red w/green (ignition system) and Green w/red (voltage regulator) wires while in START and ON. With the starter relay's "I" wire as a backup.
Easy enough to verify of course, if we grab an available switch and ohm it out in both positions. Something I admittedly have not done in 30 years or so. Happy in my belief that it was working that way!
Happy (well, semi-unhappily!) to be determined wrong so I can give more accurate info from now on.

Unfortunately the three switches I used to have sitting in the drawer next to my computer, do not seem to be in the expected place. Hmm, now where did I put those pesky things...

Thanks James. Looking forward to debating this further. Very interested in more of the gory details actually.

Paul

 

[DirtDonk]

Ok, I could not leave well enough alone, and lacking better sense, I went out to the garage and dug up a new replacement switch.

Tested it held in the vise, because I wanted to hold it steady during one aspect especially. To your comments on the Mustang switches dropping out during start, this might be a function of individual switches. This one will in fact drop out the ON/RUN circuit while in START, but only at the very far end of the start position.
But for at least half of the stroke, the ON/RUN circuit remains fully active well past the initial stage that the key is in the START position and starter would be spinning.

So maybe we have, yet again, another version of "it's a floor wax AND a dessert topping" or a "YRMV" situation. Where what works for one, does not work for another.
But at least for this switch, the ignition and regulator wires would/might/could remain energized during START.

Paul

 

[DirtDonk]

Now someone with more dexterity, and a more flexible spine, can test one in-situ on their rig and see how far the key has to go before the circuit drops out.
Ain't gonna' be me, I can tell you that!

Paul

 

[DirtDonk]

Silly me. You wouldn’t have to get into the dash to figure this out.
Simply disconnect the brown wire from the starter relay, put your voltmeter in there and have somebody turn the key to start.
If you still have 12v on the wire while the starter is cranking (and you are standing carefully to the side of course!) then you can test prove/disprove the theory.
If you disconnect the red with blue stripe wire as well, you could just test voltage on the brown wire, while the helper turns the key to various positions in the start mode.
Maybe even pushing it as far to the right as the key will go to see if voltage drops off of the brown wire.

 

[jamesroney]

Some of the early 60's ignition switches will energize the Ignition when the key is in the Start position. Some will only do it at the beginning of the start, and some allow you to twist it past the beginning, and it will drop out at MAX start position.

@DirtDonk looks like you confirmed the above.

If you crack open a bad ignition switch, you will see how the wiper terminals work mechanically, and there's no assurance that the Ignition terminal is powered when the wiper moves to the start position.

You often hear of people that can "trick" their bronco into starting by just barely twisting the key, or by releasing the key and it suddenly fires. The vast majority of people have the ignition bypass relay wire functioning, and never know or care how it all works.

I installed a used factory 5.0 Mustang EEC-4 harness into a 68 Ford Convertible, with a high torque mini-starter. I tried to delete the fender mounted starter relay. I could not get it to start. After a lot of troubleshooting, I found that the Ignition circuit dropped out every time the key moved to the start position. I tried a couple of different switches, and they were consistently "bad."

I had a couple of Bronco switches laying around, and tested them with an Ohm-meter. Sure enough, it behaved exactly as you described. Ignition dropped out at Max start. Then I tried a cheapo replacement switch. And it kept the ignition powered no matter what. So then I got mad and busted open the old switch and looked at the contacts and wiper. But that was back in 1992. So what's that? 30 years now? Ugh.

RJM uses the S terminal purple wire an an additional relay in his harness. I think that's how he keeps the ignition energized. I'm not 100% on that, but I THINK so. I can check later when I'm not ankle deep in work.

You know I appreciate your feedback, and I enjoy disagreement. I thrive on learning, and I have learned a ton from you. So thanks.

 

[jamesroney]

Silly me. You wouldn’t have to get into the dash to figure this out.
Simply disconnect the brown wire from the starter relay, put your voltmeter in there and have somebody turn the key to start.
If you still have 12v on the wire while the starter is cranking (and you are standing carefully to the side of course!) then you can test prove/disprove the theory.
If you disconnect the red with blue stripe wire as well, you could just test voltage on the brown wire, while the helper turns the key to various positions in the start mode.
Maybe even pushing it as far to the right as the key will go to see if voltage drops off of the brown wire.

Yes. But please use the second way. 90% of the Broncos will fire up before you get a chance to sweep the switch.

But the red/blue and the brown and the BAT are all exposed at the relay. If your arms are long enough, you can test them at that location.